The article examines the importance of childhood and adolescence for health in later life against the background of the population-aging process and the debate on the social challenges expected to result from this process. In this context, it describes the findings of life course epidemiology, which suggest (among other things) that there is a connection between early organic damage and the risk of illness in middle and old age, that risks and resources accumulate throughout a person's lifespan, and that living conditions and opportunities in life influence the development of health. The article also describes the health situation of children and adolescents based on the data available in Germany, in order to draw attention to existing problems and to identify possible ways of preventing them and taking action.